Understanding and managing forage inventory needs is critical to a dairy farm to assure both adequate quantities and qualities of forage to meet the needs of various animal groups on the farm. A number of methods are in use to help determine the number of acres needed to support the forage needs of a dairy herd. The Forage Acreages Needs Calculator presented here offers a few important factors that should be considered to accurately determine acreage needs, most notably the ability to account for forage shrink losses and desired carryover.